Reconfigurable radiation densensitivity bracket systems and methods

ABSTRACT

A method and device bracket are presented for reconfigurable radiation desensitivity. The method includes: accepting a radiated wave from a source such as a transmitter, antenna, microprocessor, electrical component, integrated circuit, camera, connector, or signal cable; in response to the radiated wave, creating a first current per units square (I/units 2 ) through a groundplane of an electrical circuit such as a printed circuit board (PCB), display, connector, or keypad; accepting a control signal; and, in response to the control signal, creating a second I/units 2  through the groundplane. This step couples the groundplane to a bracket having a selectable effective electrical length. Typically, the groundplane is coupled to a bracket with a fixed physical length section to provide a combined effective electrical length responsive to the fixed physical length and the selectable effective electrical length. The coupling mechanism can result from transistor coupling, p/n junction coupling, selectable capacitive coupling, or mechanically bridging.

RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 10/940,206, filed Sep. 14, 2004, by Gregory Poilasne and JordiFabrega-Sanchez, which is hereby incorporated by reference. U.S.application Ser. No. 10/940,206 is a continuation-in-part application ofU.S. application Ser. No. 10/775,722, filed Feb. 9, 2004, by JordiFabrega-Sanchez, Stanley S. Toncich and Allen Tran, which is herebyincorporated by reference. U.S. application Ser. No. 10/775,722 is acontinuation-in-part application of U.S. application Ser. No.10/120,603, filed Apr. 9, 2002, by Jordi Fabrega-Sanchez, Stanley S.Toncich and Allen Tran, which is hereby incorporated by reference, whichclaims the benefit of U.S. Provisional Application 60/283,093, filedApr. 11, 2001, which is hereby incorporated by reference.

In addition, this application relates to the following U.S. applicationsand patents, which are hereby incorporated by reference: “ReconfigurableRadiation Desensitivity Bracket Systems and Methods”, filed on the sameday and having the same inventors as the present application; U.S. Pat.No. 6,690,176, issued Feb. 10, 2004, by Stanley S. Toncich, entitled“Low Loss Tunable Ferro-Electric Device and Method of Characterization”;U.S. Pat. No. 6,765,540 B2, issued Jul. 20, 2004, by Stanley S. Toncich,entitled “Tunable Antenna Matching Circuit”; application Ser. No.09/927,136, filed Aug. 10, 2001, by Stanley S. Toncich, entitled“Tunable Matching Circuit”; application Ser. No. 10/076,171, filed Feb.12, 2002, by Stanley S. Toncich, entitled “Antenna Interface Unit”; andapplication Ser. No. 10/117,628, filed Apr. 4, 2002, by Stanley S.Toncich and Allen Tran, entitled “Ferroelectric Antenna and Method forTuning Same”.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to wireless communication and, moreparticularly, to wireless communication antennas.

2. Description of the Related Art

The size of portable wireless communications devices, such astelephones, continues to shrink, even as more functionality is added. Asa result, the designers must increase the performance of components ordevice subsystems and reduce their size, while packaging thesecomponents in inconvenient locations. One such critical component is thewireless communications antenna. This antenna may be connected to atelephone transceiver, for example, or a global positioning system (GPS)receiver.

Wireless communications devices are known to use simple cylindrical coilor whip antennas as either the primary or secondary communicationantennas. Inverted-F antennas are also popular. Many conventionalwireless telephones use a monopole or single-radiator design with anunbalanced signal feed. This type of design is dependent upon thewireless telephone printed circuit boards groundplane and chassis to actas the counterpoise. A single-radiator design acts to reduce the overallform factor of the antenna. However, the counterpoise is susceptible tochanges in the design and location of proximate circuitry, andinteraction with proximate objects when in use, i.e., a nearby wall orthe manner in which the telephone is held. As a result of thesusceptibility of the counterpoise, the radiation patterns andcommunications efficiency can be detrimentally impacted. Even if abalanced antenna is used, so that the groundplanes of proximatecircuitry are not required as an antenna counterpoise, radiation patternand radiation-susceptible circuitry issues remain.

This problem is compounded when an antenna, or a group of antennasoperate in a plurality of frequency bands. State-of-the-art wirelesstelephones are expected to operate in a number of differentcommunication bands. In the US, the cellular band (AMPS), at around 850megahertz (MHz), and the PCS (Personal Communication System) band, ataround 1900 MHz, are used. Other communication bands include the PCN(Personal Communication Network) and DCS at approximately 1800 MHz, theGSM system (Groupe Speciale Mobile) at approximately 900 MHz, and theJDC (Japanese Digital Cellular) at approximately 800 and 1500 MHz. Otherbands of interest are GPS signals at approximately 1575 MHz, Bluetoothat approximately 2400 MHz, and wideband code division multiple access(WCDMA) at 1850 to 2200 MHz.

To dampen the effects of radiation upon proximate circuitry it is knownto attach so-called bracket, or radiation-parasitic, elements to agroundplane. Typically, these “brackets” are used to evenly distributecurrent through the groundplane associated with a radiated wave.Alternately stated, the brackets are used to prevent any particular spoton a circuit board, chassis, or keyboard from becoming too sensitive toradiation-induced current. It is difficult, if not impossible, to designa wireless device to minimize the interaction between antenna radiationand susceptible circuitry in every one of its communication bands. As aresult, a conventional design must be optimized for one particularcommunication band, or the design must be compromised to have for some(minimal) effect in every communication band of interest.

It would be advantageous if groundplane sensitivity to radiation-inducedcurrent could be minimized for every frequency of operation.

It would be advantageous if groundplane sensitivity to radiation-inducedcurrent could be tuned in response to changes in frequency, or inresponse to one particular area becoming too sensitive.

It would be advantageous if radiation desensitivity brackets could bemade reconfigurable, to minimize the sensitivity of proximate circuitryat every frequency of radiation.

SUMMARY OF THE INVENTION

The present invention describes a reconfigurable radiation desensitivitybracket that can be added to the groundplane of a circuit proximate to aradiation source, to minimize the effects of radiation-induced currents.The bracket can be selectively tuned or switched in response to changesin frequency. Alternately considered, the bracket isspace-reconfigurable to selectively redistribute current flow throughthe groundplane associated with radiated waves.

Accordingly, a method is presented for reconfigurable radiationdesensitivity. The method comprises: accepting a radiated wave from asource such as a transmitter, antenna, microprocessor, electricalcomponent, integrated circuit, camera, connector, or signal cable; inresponse to the radiated wave, creating a first current per units square(I/units²) through a groundplane of an electrical circuit such as aprinted circuit board (PCB), display, connector, or keypad; accepting acontrol signal; and, in response to the control signal, creating asecond I/units² through the groundplane, different from the firstI/units². For example, the second I/units² can be made significantlysmaller if the groundplane is coupled to a bracket having a selectableeffective electrical length.

Typically, the groundplane is coupled to a bracket with a fixed physicallength section to provide a combined effective electrical lengthresponsive to the fixed physical length and the selectable effectiveelectrical length. The coupling mechanism can be through a transistor,or as a result of p/n junction coupling, selectable capacitive coupling,or mechanically bridging. In one aspect, the groundplane is coupled to abracket with a plurality of selectable electrical length sections, whichpermits series connections, parallel connections, or combinations ofseries and parallel connection configurations. In other aspects, thegroundplane is coupled to a bracket with a plurality of fixed physicallength sections.

Additional details of the above-described method and a device with areconfigurable radiation desensitivity bracket are provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of the present invention device witha reconfigurable radiation desensitivity bracket.

FIG. 2 is a schematic block diagram of the bracket of FIG. 1.

FIG. 3 is a schematic block diagram of a first variation of the bracketof FIG. 1.

FIG. 4 is a schematic block diagram of a second variation of the bracketof FIG. 1.

FIG. 5 is a schematic block diagram of a third variation of the bracketof FIG. 1.

FIG. 6 is a schematic block diagram of a fourth variation of the bracketof FIG. 1.

FIG. 7 is a schematic block diagram illustrating a fifth variation ofthe bracket of FIG. 1.

FIG. 8 is a schematic block diagram of a sixth variation of the bracketof FIG. 1.

FIG. 9 is a schematic block diagram illustrating a seventh variation ofthe bracket of FIG. 1.

FIG. 10 is a schematic diagram illustration some combinations ofseries-connected and parallel-connected FELS.

FIG. 11 is a plan view schematic diagram illustrating a bracket designwhere a plurality of fixed electrical length sections form a matrix ofadjoining conductive areas.

FIG. 12 is a perspective cutaway view illustrating a bracket chassisdesign.

FIG. 13 is a perspective drawing illustrating some exemplary FELSvariations.

FIGS. 14A and 14B are diagrams illustrating the present inventionbracket redistributing radiation-induced current flow in a groundplane.

FIG. 15 is a flowchart illustrating the present invention method forreconfigurable radiation desensitivity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic block diagram of the present invention device witha reconfigurable radiation desensitivity bracket. The device 100comprises a radiation source 102 and an electrical circuit 104 having agroundplane 106. A reconfigurable radiation desensitivity bracket 108 iscoupled to the groundplane 106. The electrical circuit 104 may becomponents, such as integrated circuits (ICs), resistors, transistors,and the like, mounted on a printed circuit board (PCB). Otherwise, theelectrical circuit 104 may be a display, a connector, or keypad, to namea few examples. The radiation source 102 may be a transmitter, antenna,microprocessor, electrical component, camera, connector, signal cable,or IC, to name a few conventional sources.

Two primary uses of the present invention bracket are for use in aportable or base station wireless device, where circuitry is susceptibleto radiating elements such as an antenna, transmitter, transmittercomponent such as a transistor, inductor, resistor, or changes in theenvironment around a radiating element, to list a few examples. Forexample, unshielded receiver circuitry is known to be susceptible toradiating elements. Another use for the bracket is inmicroprocessor-driven computing devices, such as a personal computer.Here, susceptible circuitry can be protected, using the presentinvention bracket, from a radiation source such as a power supply,high-speed ICs, or network interfaces.

One general purpose of the bracket 108 is to evenly distributegroundplane currents that are generated as a result of radiatedemissions, or confine the currents to predetermined areas of thegroundplane. For this reason, the bracket 108 is termed a radiationdesensitivity bracket, as radiation-generated current flow through agroundplane often makes a device susceptible to proximate objects thatinterrupt and modify current flow patterns. That is, the bracket acts todistribute current flow so as make the groundplane less susceptible toproximate objects. In other aspects, the bracket can be used tointentionally direct radiation-induced current flow to particular areasof the groundplane, for example, to a shielded area of the groundplanethat is not susceptible to proximate objects such as a user's hand or awall that may be temporarily located nearby.

FIG. 2 is a schematic block diagram of the bracket 108 of FIG. 1.Generally, the bracket 108 has a selectable effective electrical length200. The electrical length 200 is the measurement of wavelength, orwavelength portion. The electrical length is directly proportional tofrequency, and is modified by the dielectric constant of the materialthrough which the radiated wave travels to reach the bracket 108. Forexample, the bracket may be tuned to have either an electrical length200 a or electrical length 200 b. As can be appreciated by those skilledin the art, the bracket, in combination with the attached groundplane,forms parasitic element that has a radiation susceptance or sensitivitythat is dependent upon the frequency of radiation. That is, theinteraction of a radiated wave with the groundplane/bracket combinationis dependent upon the electrical length of the bracket. Every bracket108 includes a selectable electrical length section 204 having a distalend 206, a proximal end 208, a control input on line 210 to acceptcontrol signals, and a selectable effective electrical length 200responsive to the control signals on line 210. The bracket is termedconfigurable in that it may include switch elements, tunable elements,or both. As explained in detail below, the electrical length of thebracket can be manipulated using either the switchable or tunableelements.

The selectable electrical length section (SELS) 204 can be a couplingelement such as FET, bipolar transistor, PIN diode, ferroelectriccapacitor, varactor diode, or microelectromechanical system (MEMS)switch. The electric length of the SELS 204 is dependent upon more thanjust the physical length 212 of the section. That is, the couplingaction of the SELS 204 includes a reactance or imaginary impedancecomponent that can be varied to change the electrical length. Note, aMEMS switch may be used a variable gap capacitor by partially closingthe switch.

Returning to FIG. 1, a desensitivity control circuit 110 has an input online 112 to accept frequency selection commands and an output on line210, connected to the selectable effective length section 204. Thedesensitivity control circuit 110 supplies control signals in responseto the frequency selection commands.

FIG. 3 is a schematic block diagram of a first variation of the bracket108 of FIG. 1. In this variation, the bracket 108 further includes afixed electrical length section (FELS) 300 having a distal end 302, aproximal end 304, and a fixed physical length 306. The combination ofthe selectable electrical length section 204 and the fixed electricallength section 300 provides a combined selectable effective electricallength 308 responsive to the control signal on line 210. That is, theoverall electrical length 308 is a combination of the physical length306 of the FELS 300 and the electrical length 200 of the SELS 204, whichmay be physical length, if enabled as a MEMS for example, or areactance, if enabled as a varactor diode for example.

FIG. 4 is a schematic block diagram of a second variation of the bracket108 of FIG. 1. The bracket 108 may include a plurality of selectableelectrical length sections 204. Although three SELS' 204 are shown, theinvention is not limited to any particular number. As shown, the SELS'204 are connected to the groundplane 106.

FIG. 5 is a schematic block diagram of a third variation of the bracket108 of FIG. 1. As shown, the three SELS' 204 are series-connected to thegroundplane 106. Note, although the series of SELS' is shown asopen-connected (unterminated), in other aspects both ends of the bracket108 may be connected to the groundplane 106 or other circuitry (notshown). In other aspects not shown, the connections between individualSELS' 204 in the series may be terminated in the groundplane 106.

FIG. 6 is a schematic block diagram of a fourth variation of the bracket108 of FIG. 1. As shown, the three SELS' 204 are parallel-connected tothe groundplane 106. In other aspects not shown, both ends of one or allthe SELS' 204 may be terminated in the groundplane.

FIG. 7 is a schematic block diagram illustrating a fifth variation ofthe bracket 108 of FIG. 1. Here, SELS 204 a is connected to thegroundplane 106, SELS' 204 b and 204 c are series-connected to thegroundplane 106, and SELS' 204 d and 204 e are parallel-connected to thegroundplane 106. Note, although each configuration of SELS' 204 is shownas open-connected (unterminated), in other aspects both ends of eachconfiguration may be connected to the groundplane 106 or other circuitry(not shown).

FIG. 8 is a schematic block diagram of a sixth variation of the bracket108 of FIG. 1. In this aspect, the bracket 108 includes a plurality offixed electrical length sections 300. As shown, two FELS' 300 areseries-connected through an intervening SELS 204. Note, although theseries of sections is shown as open-connected (unterminated), in otheraspects both ends of the bracket may be connected to the groundplane 106or other circuitry (not shown), or the connections between sections maybe terminated in the groundplane 106.

FIG. 9 is a schematic block diagram illustrating a seventh variation ofthe bracket 108 of FIG. 1. As shown, FELS 300 a and 300 b areparallel-connected to the groundplane 106 through separate SELS' 204 aand 204 b, respectively. Alternately, FELS' 300 c and 300 d areparallel-connected through a single SELS 204 c. Note, although eachconfiguration of sections is shown as open-connected (unterminated), inother aspects both ends of each configuration may be connected to thegroundplane 106 or other circuitry (not shown).

FIG. 10 is a schematic diagram illustration some combinations ofseries-connected and parallel-connected FELS' 300.

FIG. 11 is a plan view schematic diagram illustrating a bracket design1100 where a plurality of fixed electrical length sections form a matrixof adjoining conductive areas 1102. For example, the adjoiningconductive areas may part of a wireless device keyboard that is mountedoverlying PCB groundplane 106. The spaces, represented withcross-hatched lines, are the individual keypads. In this aspect, theadjoining conductive areas 1102 are the FELS'. The bracket 1100 alsoincludes a plurality of selectable electrical length sections 204 thatare used to couple between fixed electrical length sections 1102. Avariety of connection configurations are shown, but the examples are notexhaustive of every possible combination. At least one of the selectableelectrical length sections 204 is coupled to the groundplane 106.Alternately, a FELS, enabled as a screw or wire (not shown), forexample, may connect the bracket 1100 to the groundplane 106.

FIG. 12 is a perspective cutaway view illustrating a bracket chassisdesign 1200. A chassis 1202 surrounds the electrical circuit 104, andfunctions as a bracket element. A third fixed electrical length section300 c is a conductive trace, conductive paint, or plating formed on thechassis 1200, coupled to the groundplane 106 through a SELS 204. Asshown, SELS 204 is connected to a first FELS 300 a, enabled as aconductive trace of a PCB, a second FELS 300 b, enabled as a screw,connects FELS 300 a to 300 c. In other aspects, the FELS 300 b can be aspring-loaded clips, pogo pin, or a conductive pillow (gasket). Avariety of other bracket configurations are possible that make use ofthe chassis as a bracket element, as would be understood by thoseskilled in the art in light of the above-mentioned examples.

FIG. 13 is a perspective drawing illustrating some exemplary FELSvariations. The FELS 300 can be a conductive metal member that issoldered or tension mounted to a bracket or groundplane. The metal formcan be straight 1300, L-shaped 1302, or O-shaped member 1304. Othershapes, or combinations of shapes are possible. Some shapes aredependent upon the surrounding area available. In addition, the FELS maybe a wire 1306, a fastener, such as a screw 1308, conductive pillow(gasket) 1312, or a conductive element trace or paint 1310 formed on aPCB or chassis. These are just a few examples of FELS elements. Anyelement capable of conducting an electrical current is potentiallycapable of acting as a FELS.

Functional Description

FIGS. 14A and 14B are diagrams illustrating the present inventionbracket redistributing radiation-induced current flow in a groundplane.The vertical dimension illustrates current flow (I). The current throughan area (unite) is one possible measure of current or currentdistribution, for example, A/in². However, other measurements of currentcan be used to illustrate the invention. In FIG. 14A, a relatively highcurrent flow in shown in one particular region as a result of a sourceradiating at 890 MHz. In response to enabling the bracket 108, thecurrent flow is redistributed, as shown in FIG. 14B. The bracket may beconsidered frequency reconfigurable, as a different electrical lengthmay be used for different radiated frequencies. Alternately, the bracketmay be considered space-reconfigurable, as it can be used toredistribute current flow to different regions of the groundplane. Forexample, the bracket 108 may be tuned to redistribute current (as shownin FIG. 14A) after device is moved near a proximate object, to createthe current pattern shown in FIG. 14B.

FIG. 15 is a flowchart illustrating the present invention method forreconfigurable radiation desensitivity. Although the method is depictedas a sequence of numbered steps for clarity, no order should be inferredfrom the numbering unless explicitly stated. It should be understoodthat some of these steps may be skipped, performed in parallel, orperformed without the requirement of maintaining a strict order ofsequence. The method starts at Step 1500.

Step 1502 accepts a radiated or transmitted wave. Step 1504, in responseto the radiated wave, creates a first current per units square(I/units²) through a groundplane of an electrical circuit. That is,current flow is induced as a result of the wave radiated in Step 1502.Step 1506 accepts a control signal. Step 1508, in response to thecontrol signal, creates a second I/units² through the groundplane,different from the first I/units². Alternately stated, the I/units² iseither frequency or space-reconfigurable, as mentioned above. As notedabove, the choice of the current-related measurement is somewhatarbitrary, and the invention can also be expressed in other units ofmeasurement related to current, energy, or field strength.

Step 1502 accepts a radiated wave from a source such as a transmitter,antenna, microprocessor, electrical component, integrated circuit,camera, connector, and signal cable. Step 1504 creates the firstI/units² through a groundplane of an electrical circuit such ascomponents mounted on a printed circuit board (PCB), display, connector,or keypad.

In one aspect, Step 1508 creates a second I/units² through thegroundplane of an electrical circuit by coupling the groundplane to abracket having a selectable effective electrical length. Further,groundplane can be coupled to a bracket with a fixed physical lengthsection to provide a combined effective electrical length responsive tothe fixed physical length and the selectable effective electricallength.

In other aspects, Step 1508 couples the groundplane to a bracket with aplurality of selectable electrical length sections. For example, theplurality of selectable electrical length sections can be coupled in aconfiguration such as connected to the groundplane, series-connected,parallel-connected, or combinations of the above-mentioned connectionconfigurations. Likewise, Step 1508 may couple the groundplane to abracket with a plurality of fixed physical length sections. Again, theplurality of fixed electrical length sections may be connected to thegroundplane, series-connected, parallel-connected, or combinations ofthe above-mentioned connection configurations.

In a different aspect, Step 1508 couples through a mechanism such astransistor coupling, p/n junction coupling, selectable capacitivecoupling, variable gap coupling, or mechanically bridging. For example,a transistor may act as a switch, buffer, current amplifier, voltageamplifier, or reactance element. The transistor coupling may beaccomplished with a bipolar transistor or FET. The p/n junction couplingmay be accomplished with a PIN diode. The capacitive coupling may beaccomplished with a varactor diode or ferroelectric capacitor, and themechanical bridging may be accomplished with a MEMS or other type ofmechanical switch. The variable gap coupling may be enabled using a MEMSswitch.

A device with a reconfigurable radiation desensitivity bracket, andcorresponding reconfigurable radiation desensitivity method have beenprovided. Some examples of specific bracket shapes and schematicarrangements have been presented to clarify the invention. Likewise,some specific physical implementations and uses for the invention havebeen mentioned. However, the invention is not limited to just theseexamples. Other variations and embodiments of the invention will occurto those skilled in the art.

1. A method for reconfigurable radiation desensitivity, the methodcomprising: accepting a radiated wave; in response to the radiated wave,creating a first current per units square (I/units²) through agroundplane of an electrical circuit; accepting a control signal; and,in response to the control signal, creating a second I/units² throughthe groundplane, different from the first I/units².
 2. The method ofclaim 1 wherein creating a first I/units² through the groundplane of anelectrical circuit includes creating a first I/units² through agroundplane of an electrical circuit selected from the group includingcomponents mounted on a printed circuit board (PCB), display, connector,and keypad.
 3. The method of claim 1 wherein accepting a radiated waveincludes accepting a radiated wave from a source selected from the groupincluding a transmitter, antenna, microprocessor, electrical component,integrated circuit, camera, connector, and signal cable.
 4. The methodof claim 1 wherein creating a second I/units² through the groundplane ofan electrical circuit, in response to the control signal, includescoupling the groundplane to a bracket having a selectable effectiveelectrical length.
 5. The method of claim 4 wherein coupling thegroundplane to a bracket having a selectable effective electrical lengthincludes coupling the groundplane to a bracket with a fixed physicallength section to provide a combined effective electrical lengthresponsive to the fixed physical length and the selectable effectiveelectrical length.
 6. The method of claim 4 wherein coupling thegroundplane to a bracket having a selectable effective electrical lengthincludes coupling the groundplane to a bracket with a plurality ofselectable electrical length sections.
 7. The method of claim 6 whereincoupling the groundplane to a bracket with a plurality of selectableelectrical length sections includes connecting the plurality ofselectable electrical length sections in a configuration selected fromthe group including connected to the groundplane, series-connected,parallel-connected, and combinations of the above-mentioned connectionconfigurations.
 8. The method of claim 6 wherein coupling thegroundplane to a bracket having a selectable effective electrical lengthincludes coupling the groundplane to a bracket with a plurality of fixedphysical length sections.
 9. The method of claim 8 wherein coupling thegroundplane to a bracket with a plurality of fixed physical lengthsections includes connecting the plurality of fixed electrical lengthsections to a selectable electrical length section in a configurationselected from the group including connected to the groundplane,series-connected, parallel-connected, and combinations of theabove-mentioned connection configurations.
 10. The method of claim 4wherein includes coupling the groundplane to a bracket having aselectable effective electrical length includes coupling through amechanism selected from the group including transistor coupling, p/njunction coupling, selectable capacitive coupling, variable gapcoupling, and mechanically bridging.